sum elements array with step numy

import numpy as np
matrix=np.ones((10,10))
print(matrix.sum(axis=0))
print(matrix.sum(axis=1))

>>> np.sum([[0, 1], [0, 5]])
6
>>> np.sum([[0, 1], [0, 5]], axis=0)
array([0, 6])
>>> np.sum([[0, 1], [0, 5]], axis=1)
array([1, 5])

b = [sum(a[current: current+5]) for current in xrange(0, len(a), 5)]